The Unusual Nature of Recent Snowpack Declines in the North American Cordillera (Science)

[jpak]

http://www.sciencemag.org/content/333/6040/332.abstract

The Unusual Nature of Recent Snowpack Declines in the North American Cordillera

Gregory T. Pederson, Stephen T. Gray, Connie A. Woodhouse, Julio L. Betancourt, Daniel B. Fagre, Jeremy S. Littell, Emma Watson, Brian H. Luckman, Lisa J. Graumlich

Abstract

In western North America, snowpack has declined in recent decades, and further losses are projected through the 21st century. Here, we evaluate the uniqueness of recent declines using snowpack reconstructions from 66 tree-ring chronologies in key runoff-generating areas of the Colorado, Columbia, and Missouri River drainages. Over the past millennium, late 20th century snowpack reductions are almost unprecedented in magnitude across the northern Rocky Mountains and in their north-south synchrony across the cordillera. Both the snowpack declines and their synchrony result from unparalleled springtime warming that is due to positive reinforcement of the anthropogenic warming by decadal variability. The increasing role of warming on large-scale snowpack variability and trends foreshadows fundamental impacts on streamflow and water supplies across the western United States.

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[wtbymark]

1. The Sierra's did surprisingly well

150% snow pack this year, in fact, today there is snow on the mountains in Tahoe. It is more water than we've had in 10 years. Truckee river 2 ft above normal for mid-july. We need another 5 years of this.